A federal investigation revealed that a non-injury oil tanker fire that resulted in millions of dollars in damages was caused by a lithium-ion battery in a handheld radio.
The National Transportation Safety Board (NTSB) found that the lithium-ion battery in the radio exploded during a thermal runaway event and started the fire which resulted in $3 million in damage to the vessel.
Vessel master notices something is amiss on the bridge
On Nov. 11, 2022, the oil tanker S-Trust docked at the Genesis Port Allen Terminal Dock in Baton Rouge, Louisiana, with 464,926 barrels of high-sulfur fuel oil to offload.
Personnel began managing the transfer of the oil barrels from the cargo control room shortly after the tanker docked.
Two days later, the vessel’s master was working at a desk in his office, which was one level below the tanker’s bridge. There was a video monitor next to the desk that showed closed-circuit camera feeds from throughout the tanker. One of those feeds was from the vessel’s bridge.
As the master looked at the feed from the bridge, he noticed it was no longer visible, so he went to the bridge to investigate. When he opened the door to the bridge, smoke came out activating a nearby smoke detector.
The master quickly closed the door, went to the cargo control room and told the chief mate to stop all cargo operations. The chief mate ceased operations before making a call for help. The West Baton Rouge Fire Department was dispatched to fight the fire.
Fire damages multiple systems beyond repair
Meanwhile, the master returned to the bridge to fight the fire. On the way there, he used his radio to notify the rest of the crew about the fire on the bridge deck. Once he arrived back at the bridge, the master used two side doors on opposite sides of the room to evaluate the situation. He could see that the fire was coming from the communications table where the handheld radios were stored.
By the time the master finished evaluating the situation, other members of the crew arrived to help fight the fire. The master organized them into two fire teams who would fight the fire from the two side doors he used to evaluate the situation earlier.
The two fire teams managed to put the fire out shortly before the fire department arrived. Emergency responders investigated the vessel and confirmed that the fire was extinguished.
Investigators from the Coast Guard and the Bureau of Alcohol, Tobacco, Firearms and Explosives (ATF) found extensive damage throughout the bridge from both the smoke and the heat from the flames. The navigation, communication and alarm systems were damaged beyond repair.
There were no injuries and no damage done to any of the lower decks.
Battery explosions seen on video footage
Video footage reviewed by the NTSB showed an orange flash immediately followed by a puff of smoke near the communications table around the time the fire started. Following that initial flash, smoke could be seen rising up and increasing in volume and thickness. A few minutes later another orange flash could be seen.
After the second flash, a flaming object could be seen flying off the table and onto the starboard side of the bridge. The burning object landed on the deck in front of the lifejacket locker where it continued to burn, eventually causing the fire to spread.
The S-Trust carried 20 ultra high frequency (UHF) handheld radios for the crew to use to communicate during vessel operations. An inventory conducted after the incident found that there were 27 7.4-volt batteries for these radios with 14 of them having lithium-ion cells and 13 containing nickel-metal hydride cells.
While the radios, batteries, cells and chargers were manufactured in several different countries, all of them were certified by Underwriters Laboratories to be safe for use.
NTSB: Thermal runaway caused battery cells to explode
When investigators examined the communications table on the bridge, they found the remains of a lithium-ion battery charger and a nickel-metal hydride battery charger. Taking a closer look, they found the remains of three batteries among the charger remains: one nickel-metal and two lithium-ion.
All six of the nickel-metal battery’s cells were found among the charger remains. Of the two lithium-ion batteries, both cells of one battery were found but neither of the second battery’s two cells could be found.
ATF investigators reported that the cause of the fire was an explosion involving a lithium-ion battery located on the communication desk. The investigators also thoroughly examined other electronic devices in the area and ruled them out as potential sources of the fire.
The NTSB agreed with the ATF report, pointing to the fact that “lithium-ion battery cell explosions are typically caused by a thermal runaway, a chemical reaction that can cause the cell to ignite and explode.”
Thermal runaways can spontaneously occur if a lithium-ion battery cell gets damaged, shorted, overheated, or is defective or overcharged, according to the NTSB.
How to prevent, fight fires caused by lithium-ion batteries
To help prevent thermal runaways and the fires they cause, the NTSB recommended:
- following manufacturer’s instructions for the care and maintenance of the batteries
- properly disposing of damaged batteries
- avoiding unsupervised charging, and
- keeping batteries and chargers away from heat sources and flammable materials.
The NTSB also stated that employers should “ensure that lithium-ion batteries and devices that use lithium-ion battery packs are certified by Underwriters Laboratory or another recognized organization.”
If a lithium-ion battery fire does occur, the NTSB said responders can “attempt to extinguish the fire with water, foam, CO2, or other dry chemical or powdered agents designed for use on Class A (combustible) fires.”
In cases where the fire can’t be extinguished, the NTSB recommended that the pack be allowed to burn in a controlled manner “including by watching for nearby cells that may also experience thermal runaway and extinguishing other combustibles that may catch on fire.”